This invention relates to phthalocyanines and more particularly to substituted phthalocyanines exhibiting strong absorption maxima in the near infra-red region of the electromagnetic spectrum, for example in the region between 750 and 900 nm.
According to the invention, there are provided phthalocyanine compounds of the formula:
MkPc(xe2x80x94Oxe2x80x94Rxe2x80x94Oxe2x80x94)x(xe2x80x94YR1)y(xe2x80x94Z)m(xe2x80x94SO3A)nxe2x80x83xe2x80x83(1)
wherein MkPc is a phthalocyanine nucleus of the formula: 
in which M represents a metal atom, a halogeno-metal group, an oxy-metal group or hydrogen and
k is the inverse of half the valency of M;
R represents a substituted or unsubstituted 1,2-arylene group;
Y represents oxygen or sulphur;
R1 represents a substituted or unsubstituted hydrocarbyl group;
Z represents a halogen or hydrogen;
A represents hydrogen, a metal or substituted or unsubstituted ammonium;
x represents an integer from 1 to 8;
y represents an integer from 0 to 14;
m represents an integer from 0 to 14;
n represents an integer from 0 to 32;
the sum of 2x, y and m not exceeding 16, and the groups or atoms xe2x80x94Oxe2x80x94Rxe2x80x94Oxe2x80x94, xe2x80x94YR1 and Z are attached to the peripheral carbon atoms numbered 1 to 16 in Formula 2, with the proviso that when n is zero, at least one 1 ,2-arylene group represented by R carries at least one alkyl group containing at least four carbon atoms.
As indicated by Formula 2 above, the phthalocyanine nucleus of the compounds of the invention may be metal-free or may contain a complexed metal, halogeno-metal or oxy-metal, that is to say it may carry two hydrogen atoms at the centre of the nucleus or it may carry one or two metal atoms, halogeno-metal groups or oxy-metal groups complexed within the centre of the nucleus. Where a metal atom, halogeno-metal or oxy-metal group is complexed within the centre of the nucleus, the atom or group may be mono or divalent. Where an ordinarily trivalent or higher valency metal is present, the valency above 2 is satisfied by one or more halogen or oxy groups. Halogeno-metal groups include fluoro-metal, bromo-metal, iodo-metal and particularly chloro-metal groups. Oxy-metal groups include metal compounds with one or more of divalent oxygen and monovalent oxygen-containing groups, for example, hydroxy groups, alkoxy, especially C1-4 alkoxy, groups and aryloxy, especially phenoxy and naphthoxy, groups. The alkoxy and aryl oxy groups may be unsubstituted or may be substituted by one or more substituents selected from the list of substituents for R and R1 given below. Examples of suitable metals, halogeno-metals and oxy-metals include lithium, sodium, copper, nickel, zinc, manganese, iron, chloro-iron, chloro-aluminium, tin, lead, vanadyloxy and titanyloxy.
Optionally substituted 1,2-arylene groups which may be represented by R include naphthylene and especially phenylene groups. The value of x is preferably 4 or 8.
Optionally substituted hydrocarbyl groups which may be represented by R1 include optionally substituted alkyl groups and particularly optionally substituted aryl groups, for example naphthyl and especially phenyl groups. The preferred value of y is in the range from 0 to 8.
When either or both of R and R1 are substituted, the substituents may be one or more substituents selected from the group consisting of C1-20-alkyl, C1-20-alkoxy, C2-20-alkenyl, C1-20-alkylthiol, C1-20-alkoxycarbonyl, hydroxy C1-4-alkoxy, phenyl, benzyl, phenylthio, fluoro, chloro, bromo, xe2x80x94CN, xe2x80x94NO2, xe2x80x94CF3, xe2x80x94COR2, xe2x80x94COOR2, xe2x80x94CONR2R3, xe2x80x94SO2R2, xe2x80x94SO2NR2R3, NR2R and xe2x80x94OR2 in which R2 and R3 are each independently H, C1-4-alkyl or phenyl. Preferred substituents for R include C1-20-alkyl groups.
Halogen atoms which may be represented by Z include fluorine, bromine, iodine and, especially, chlorine. The preferred value of m is in the range from 0 to 8.
Metals which may be represented by A include alkaline earth metals, and, especially, the alkali metals. It is preferred that A is sodium or hydrogen.
When A represents substituted ammonium, the ammonium group is substituted by from 1 to 4 groups selected from up to C18 alkyl groups, preferably up to C4 alkyl groups; and phenyl groups. Each substituent may be further substituted by one or more substituents selected from the list of substituents for R and R1, above.
Compounds of the invention containing xe2x80x94SO3A groups, which may be attached directly to the peripheral carbon atoms of the phthalocyanine nucleus and/or to the pendent organic groups R and R1 are soluble in water.
In compounds of the invention which contain no sulphonic acid or sulphonate groups (n=0), at least one 1,2-arylene group represented by R carries at least one alkyl group containing at least four carbon atoms so as to provide solubility in organic liquids. Suitable alkyl groups may contain from 4 to 20, preferably from 4 to 12 and especially from 4 to 8 carbon atoms. Preferred alkyl groups include branched alkyl groups, especially tertiary alkyl groups such as t-butyl and t-octyl. For maximum solubility, it is preferred that each 1,2-arylene group carries at least one alkyl group having at least four carbon atoms.
It is preferred that the solubility of the sulphonate-free phthalocyanines of the invention in organic liquids is at least 3%. Preferred organic liquids are selected from aliphatic and aromatic hydrocarbons, ethers, ketones, chlorinated aliphatic and aromatic hydrocarbons, amides and substituted amides. Specific examples of suitable organic liquids are tetrahydrofuran (THF), cyclohexanone, chloroform, toluene, dichloromethane (DCM) and dimethylformamide (DMF).
As specific examples of useful phthalocyanine compounds of Formula 1,there may be mentioned the compounds: 
The phthalocyanine compounds of Formula 1 may be prepared by methods analogous to those used for the preparation of known phthalocyanine compounds. Thus, for example, an appropriately substituted phthalonitrile may be reacted with a metal or metal salt at an elevated temperature, optionally in an inert liquid and/or in the presence of catalytic materials. Sulphonation may then be effected if desired. Appropriately substituted phthalonitriles include phthalonitriles carrying twoxe2x80x94OROxe2x80x94 substituents or carrying one xe2x80x94OROxe2x80x94 substituent and optionally one or two xe2x80x94YR1 substituents. The phthalonitriles may themselves be prepared by reacting halogen-substituted phthalonitriles with catechols and, optionally, phenols.
The phthalocyanine compounds of the present invention are useful for absorbing electromagnetic radiation, especially in the near infra-red region of the spectrum, and they may be employed for this purpose in a variety of electronic devices. In this connection, it is to be noted that the optionally substituted catechol residues present in the compounds of Formula 1 provide a bathochromic effect of from 50 to 70 nm compared with the corresponding phenoxy-substituted phthalocyanines. In addition, the compounds can be used in security applications such as in printing currency or cheques, in ink jet printing, laser thermal printing, flash fusion of toners, optical data storage and as charge generating materials for laser thermal printing.